WASHINGTON -- Forget suicide bombings, chemical weapons, and even so-called "dirty" bombs that can contaminate a city center for decades with radioactive debris.

Less than two months ago, 10 men armed only with assault rifles, explosives, and stolen cell phones held downtown Mumbai hostage for 72 hours, grabbing the attention of the world. When it was over, more than 170 people were dead and hundreds more were injured.

Speaking to the Senate Homeland Security Committee on January 8, three leading U.S. security officials told Congress that the Mumbai attack suggests that such low-tech assaults are likely to be part of the terror wave of the future.

The key to the attack was low-tech weaponry guided by high-tech, but easy-to-find, cell phones. And the tactic worked.

"Low-tech attacks can achieve strategic goals, and can be dramatically enhanced by technology enablers," said Charles Allen, the chief intelligence officer of the U.S. Department of Homeland Security (DHS).

"The attackers [in Mumbai] were able to fend off responding forces, just using automatic rifles, grenades, and some IEDs [improvised explosive devices], basically the weapons of a basic infantryman," he added. "They also used satellite and cell phones to maximize effectiveness, and they monitored press coverage of the attack through wireless communication devices they had taken from hostages."

Inspiring The Wrong People

Donald Van Duyn, chief intelligence officer of the Federal Bureau of Investigation (FBI), said this successful tactic sent a very powerful message to the wrong people.

Van Duyn said investigators have learned several important lessons from this attack: Not only are simple weapons effective against police who are expecting a more sophisticated attack, but that such an attack is extraordinarily easy to copy by other groups.

"The simplest weapons can be as deadly [as weapons of mass destruction]. It comes as no surprise that a small, disciplined team of highly-trained individuals can wreak the level of havoc that we saw in Mumbai," Van Duyn said.

"Other terrorist groups will no doubt take note of and seek to emulate the Mumbai attacks," he continued. "The take-home lesson for the FBI and the DHS and law enforcement is that we need to continue to look at those large and small organizations with the right combination of capabilities and intent to carry out attacks."

The chairman of the committee, Senator Joseph Lieberman (Independent-Connecticut), asked the third witness, New York City Police Commissioner Raymond Kelly, whether this makes Mumbai a kind of turning point in what U.S. President George W. Bush calls the war on terror.

Absolutely, Kelly said. The commissioner said that as he learned more about the weapons used by the Mumbai attackers, he became increasingly impressed by the simplicity of their methods in creating so much carnage.

In fact, Kelly said, the firearms used in the assaults may not even have been automatic weapons, but semi-automatic AK-56 rifles. Yet they served their purpose well.

"These are basic weapons that created almost 500 deaths and serious injuries, so, yes, we certainly look to learn more from our federal colleagues as their study -- as their investigation -- moves forward," Kelly said. "But it could very well be a turning point in the sense that the relative simplicity of this attack is picked up by others."

What Extremists Want

Beyond the simplicity of the attacks, the DHS's Allen said, what was notable was the location of the assault and how the standoff dragged on for three days. He noted that a series of attacks on trains in and around Mumbai in July 2006, while costing more lives, didn't capture the world's imagination as did the attacks in downtown Mumbai in November.

"Here, they attacked the financial and entertainment centers of Mumbai, and they were able to galvanize the world for 72 hours. So I think what we take away from this is a very sober thought that soft targets can create, for political effect, exactly what extremists want," Allen said.

"Because it's clear that some of the Lashkar-e-Taiba [the Pakistani group blamed for the attack] at the time were -- and remain, I think -- very enthusiastic that they were able to bring great attention to their cause."

Allen, Van Duyn, and Kelly had other observations about the Mumbai attack. They spoke of Indian security officials letting down their guard and lax security at the luxury hotels that were targeted.

They also said their agencies are working even harder with foreign counterparts to prevent further attacks, and urged the U.S. public to remain vigilant to suspicious activity.

And all three agreed that the world probably hasn't heard the last of men like those who held Mumbai hostage for 72 hours.